Jinhao Fountain Pen Ink Refill Cartridges International Standard Size, 30 PCS, Black Color These ink cartridges have a neutral PH, excellent coverage, smooth flow. International standard size : These ink cartridges fit 98% fountain pen , but not fit Lamy , Parker Pen Each ink cartridge is 53 mm long and 7 mm in width. Package : 30 PCS black ink Cartridge 100% Money Back Guarantee :If you are not satisfied with this purchase , just send us a message ,we will either refund you or send your replacement .